1. Field of the Invention
The present invention relates to a magnetoresistive element and a magnetic memory. For example, the present invention relates to a magnetoresistive element which can store information by bidirectionally supplying a current thereto.
2. Description of the Related Art
A magnetic random access memory (MRAM) using a ferromagnetic material is anticipated as a nonvolatile memory having non-volatility, high-speed operation, large capacity and low power consumption. The MRAM includes a magnetic tunnel junction (MTJ) element using a tunneling magnetoresistive (TMR) effect as a memory element. The MRAM stores information according to the magnetization configuration of the MTJ element.
A conventional MRAM executing a write operation using a magnetic field by an interconnect current has the following problem. With the advance in scale reduction, a current flowing through the interconnect decreases; for this reason, it is difficult to supply a sufficient current magnetic field to the MTJ element. In addition, the size of the current magnetic field required for recording information to the MTJ element increases resulting from the scale reduction of the MTJ element. Thus, for the 126 to 256 M-bit generation, there is a theoretical limit in the in the execution of a write operation using a magnetic field by an interconnect current in an MRAM.
In order to solve the foregoing problem, an MRAM executing a write operation using spin momentum transfer (SMT) has been proposed (Document 1: U.S. Pat. No. 6,256,223). Magnetization switching by the spin momentum transfer (also referred to as spin injection) has the following advantage. Specifically, even if scale reduction of the element is made, the magnitude of current density required for magnetization switching does not increase; therefore, a high-effective write operation is possible.